It’s not manufacturing it. It’s not even transporting it from where it’s made (even if it was a very long way away).

It’s washing and drying it.

In a recent Marks and Spencer’s study, they looked at an average pair of men’s cotton briefs. They reckoned that, on average, they had a two year life and were washed 52 times a year at 60 degrees. Half of the time, they were tumble dried.

Growing the cotton accounted for 2.6% of the pant’s carbon footprint. The manufacture of the product accounted for another 12.6%. Transporting and selling the pants was another 4%.

Which leaves nearly 81%.

This is down to guy who bought and wore them.

A bit, around 3%, was created transporting it back from the shops. The rest of the carbon footprint was created by washing and drying them. The biggest chunk being tumble drying.

The average UK household uses their washing machine 274 times a year. That’s three days in every four. Using a washing machine accounts for 10% of the energy the average person uses. And 12% of the water we use, is in our washing machine.

The majority of the energy a washing machine uses – over 90% – is used to heat the water. So washing clothes at lower temperatures makes a really big difference. Reducing the heat from 60 degrees to 30 saves about half of the energy. And a few quid too.

Having a decent, reasonably new washing machine helps too. An A+ rated model uses two thirds of the energy a standard machine uses. And a new machine generally only uses half the water that a 10-year-old machine would. Since over 90% of a washing machine’s carbon footprint comes from its use, rather than it’s manufacture and disposal, buying a new, more efficient model might actually be more environmentally friendly.

On the plus side, a modern washing machine is pretty efficient with water and so washing clothes by hand generally uses more water. So you can relax and not feel guilty about not using a mangle.

Make sure you do full loads though. Doing a 3.5kg wash rather than a 3kg wash is apparently about 14% more efficient. Don’t go washing those pants on their own.

Tumble drying is really bad. A tumble dryer can use over 2kw of power for an average cycle. That’s seven times as much as a 30 degree wash. Or the same as three and a half 60 degree washes.

Ironing is also pretty power hungry, using more than ten times as much as a 100 watt light bulb. Where possible, it should be avoided, which comes as a relief to me but will probably disappoint my mother.

And then there’s how often we wash stuff.

I reckon most of us wash clothes more regularly than is strictly necessary. I’m not suggesting that we should all go feral and go in to work a bit wiffy. But I reckon that generally I could probably get two wears out of a shirt rather than one before I wash it. Certainly during winter. And if I did that, I’ve nearly halved my shirt’s carbon footprint. Result.

So then.

Try and wash your clothes less.

Within reason obviously.

Wash them at 40 degrees or, even better, 30 if your machine will do it. If you’ve got a really old knackered machine, maybe think about getting a new one. Use a washing line or drying rack instead of tumbling unless you really need to. We don’t own one and live in a tiny flat, so frankly, I don’t think you really do.